1. Field of the Invention
This invention relates to a method and apparatus for setting small objects in malleable material, and it also relates to malleable sheet materials in which small objects are set.
2. Description of the Related Art
More specifically, but not exclusively the invention relates to the setting of gem stones in precious and semi-precious metal (such as gold and silver and their alloys) sheets, which are commonly used in the jewelry industry. Examples of items of jewelry incorporating set gem stones includes pendants, lockets, brooches and the like.
Although the following discussion relates predominantly to the setting of diamonds in gold, it will be appreciated that the invention has much wider application, and indeed may be used to set any stone or other suitably shaped and sized objects in any malleable sheet material. However, the invention has most suitable application in the jewelry industry as described hereinafter.
The setting of gem stones in precious metals such as gold and silver sheet is currently a highly skilled process. To set a stone, a hole smaller than the stone is drilled through the metal sheet in which the stone is to be set, and the upper edges of said hole are then chamfered inwardly of the hole such that the stone will seat correctly in an upright position. It should be pointed out that in most cases, the stones to be set are minute, and the sheet is as thin as possible (to keep the cost of the sheet down as much as possible) and thus the intricacy of the process is often extreme.
A metal scoop is used to gouge metal from the sheet around the hole in a desired pattern, for example a four-pointed star, to enhance the aesthetic effect of the setting.
In order to ensure that the stone is set in its upright orientation, the setter may use a tacky material such as Plaszicine.RTM. or Blu-Tack.RTM. to lift a stone by its upper face and place it into the chamfered hole, which is usually at the centre of the gouged pattern. The tacky material adheres more to the finger of the setter than to the stone, and thus the sliding of the finger away from the stone once positioned in the chamfered hole releases it from said tacky material.
To secure the stone to the metal, a further gouging process is required wherein the setter uses a metal scoop to gouge material from around the hole towards the stone in a manner similar to the scooping of butter curls. In the case where a four-pointed star pattern has been previously gouged around the hole, the setter positions the stone in said hole and gouges metal from between the points of the star in a symmetrical manner. The natural deformation of the metal which results from said scooping is to curl in the direction of and over an edge of the stone, thus securing said edge. The setting process is completed by using a de-burring tool which is simultaneously rotated and urged downwardly onto each of the gouged metal portions which overlie the edges of the stone. Burr resulting from the gouging operation is removed, and the downward pressure on the malleable material deforms the gouged metal portions into small pips which overlie the edges of the stone thus securing it symmetrically in the hole.
The abovementioned process has a number of inherent disadvantages. Firstly, there is a limit to the thickness of the metal which may be used, as thinner metal is likely to be punctured and ruptured by the manual gouging operations, regardless of the skill of the setter, but reducing the thickness of the material is always desirable especially in cases where a large number of lockets, pendants, brooches and the like are produced (of the order of thousands per week), in that a slight reduction in the thickness of the metal of said items may represent a substantial saving in raw material cost for the manufacturer.
A further disadvantage which is inherent in any manual operation is the imprecise nature thereof. More specifically, it is highly unlikely that a setter will achieve an exactly symmetrical stone setting on every single occasion, and in some cases such variation may result in weak setting of the stone with obvious further consequences.